attachment_url_field.rb

# frozen_string_literal: true

module CoreBy
  module FieldExtensions
    # GraphQL field extension allows returning URL of Active Storage attachment.
    # TODO: Move to `graphql-field_attachment` gem?
    class AttachmentUrlField < GraphQL::Schema::FieldExtension
      attr_reader :attachment_assoc

      def apply
        attachment = options.fetch(:attachment) { field.original_name.to_s.sub(/_url$/, "") }

        @attachment_assoc = "#{attachment}_attachment"

        if (variant = options[:variant])
          field.argument(
            :variant,
            variant.fetch(:enum),
            required: variant.fetch(:required),
            description: "Attachment variant"
          )
        end
      end

      def resolve(object:, arguments:, **rest)
        object.preload_association(attachment_assoc => :blob)
      end

      def after_resolve(value:, arguments:, object:, **rest)
        return if value.nil?
        return value if value.is_a?(GraphQL::Execution::Interpreter::RawValue)

        CoreBy::ActiveStorage.attachment_url(value, variant: arguments[:variant]&.to_sym)
      end
    end
  end
end